[ECS] Update ecs to 1.6.0 (elastic#20792)

* Update ecs to 1.6.0

* Update fields.ecs.yml and re generate fields files

* Remove filebeat duplicated cloud.project.id

* Remove filebeat duplicated log.file.path

* Remove repeated cloud.project.id from remaining beats

* Remove duplicated x509.* fields from metricbeat

* Remove duplicated x509.* fields in packetbeat

* Remove duplicated field log.file.path from winlogbeat

* Add missing exports tests and better error message

* Run make fmt

(cherry picked from commit ef457ea)

NOTICE.txt

@@ -5491,11 +5491,11 @@ This Agreement is governed by the laws of the State of New York and the intellec
 
 --------------------------------------------------------------------------------
 Dependency : github.com/elastic/ecs
-Version: v1.5.0
+Version: v1.6.0
 Licence type (autodetected): Apache-2.0
 --------------------------------------------------------------------------------
 
-Contents of probable licence file $GOMODCACHE/github.com/elastic/ecs@v1.5.0/LICENSE.txt:
+Contents of probable licence file $GOMODCACHE/github.com/elastic/ecs@v1.6.0/LICENSE.txt:
 
 
                                  Apache License